The best you can do in the US with an X74 is a retrofit of the parts. You cannot (without monumental effort) install the chassis bracing as it is part of the chassis and not a bolt on part. Myself and 3 others I know have installed the X74 so far in 2003 cars and have not experienced any problems yet. I understand Porsche does not condone it, but it can't be worse than H&Rs